This invention relates generally to gas turbine vanes provided with cooling means and more particularly to a gas turbine vane which is cooled by a so-called gas collision cooling system in which air jets are blown at high velocity against parts such as the inner surface of the vane leading edge thereby to increase the cooling effect (as disclosed, for example, in Japanese Patent Laid-Open Publication No. 69708/1976).
A gas turbine vane generally comprises an outer hollow member in vane shape and an inner hollow member inserted into the hollow portion of the outer vane member, and a plurality of rib-like projection members (hereinafter called rib or ribs) are integrally formed on the inner wall side of the outer vane member in the vane chord direction and disposed in a row in the spanwise or radial direction to form cooling passages. The inner hollow insertion member is rigidly engaged with these ribs when it is fitted in the outer vane member, and under the thus inserted condition, a turbulence chamber is defined between the leading edge portion of the outer vane member and the leading edge portion of the insertion member.
With the general construction of the gas turbine vane as described above, when it is required to cool the turbine vane, a gas collision type vane cooling method is adopted as the vane cooling method. In this method the gas turbine vane is cooled by a gas, usually air, ejected from the outlet of a compressor. More particularly, a high speed air jet from the compressor is injected into the inner hollow member inserted into the outer vane member and then jetted into the turbulence chamber through holes formed through the leading edge portion of the insertion member thereby to cool the inner wall of the leading edge portion of the outer vane member to forcibly cool that portion by the air collision cooling effect.
The air after collision is then guided into cooling passages formed between the flank walls of the outer vane member and the inner insertion member to cool the entire flank wall of the outer vane member and is finally exhausted through exhaust holes formed at the trailing edge portion of the outer vane member.
With the gas turbine vane provided with the vane cooling means of the type described above, it is necessary to supply a relatively large amount of cooling air in order to maintain the temperature of the turbine vane below the allowable temperature. The feeding of a large amount of the cooling air indeed improves the vane cooling efficiency, but on the other hand, the temperature of a gas acting on the turbine vane is also lowered thereby undesirably lowering the output efficiency of the gas turbine. In view of these problems, a gas turbine vane provided with an improved vane cooling means consuming a relatively small amount of cooling air has been desired.